P071 Characterization of Interleukinl-17 signaling molecules in teleost

Abstract

IntroductionTeleost Interleukin-17 (IL-17) was reported to consist of seven ligands includingchracterisitic member IL-17N in teleost fish. However, IL-17 receptors and their signaling molecules (or transcription factors related to IL-17 signaling pathway) are few reported in telsosts. In mammals, IL-17 receptors lead to the recruitment of Act1 through homotypic interactions between SEFIR domains. This is turn allows the incorporation of TRAF6 into the signaling complex and activates the NF-kB transcription factor pathway. In this report, we identified seven IL-17 receptors (RA, RC-1, -2, RD-1, -2, -3 and RE), Act1 and TRAF6 from Japanese pufferfish, Takifugu rubripes using comparative genomics based on chromosomal synteny and characterized their biological activities. MethodsThe primary data is collected by Fugu genome database analysis. The intron/exon prediction by genscan is then confirmed by cloning the transcripts of the gene. Multiple alignments were generated using CLUSTAL W program. A phylogenetic tree was constructed by maximum parsimony method using MEGA 3. The expression analysis of Fugu IL-17 receptors, ACT1 and TRAF6 genes was undertaken in normal tissues or mitogen stimulated tissues. ResultsFugu IL-17RC1 and RE genes harbored on scaffold_180 and other Fugu IL-17 receptors were found to be located on independent contigs. Fugu IL-17 receptors showed a single transmembrane domain, ranging in size from 470 to 755 amino acids. Moreover, these receptors contained certain conserved the SEFIR domain. Fugu Act1 contained TRAF binding sites at the N-terminus, and Act1 had a SEFIR domain located at the C-terminus. Fugu TRAF6 ORF is predicted to encode 561 amino acids. Multiple alignment with other known TRAF6 genes revealed conservation among vertebrates. The expression pattern of Fugu IL-17 RA and RC genes were observed in almost all organs, while the other Fugu IL-17 receptor genes expressed in few organs. In particular, IL-17 receptor genes showed highly expression in the spleen. Moreover, IL-17 receptor genes showed different expression pattern in the mitogen-stimulated head kidney cells. In addition, expression analysis of Fugu Act1 and TRAF6 genes suggested that the transcription factors play important roles in inflammatory responses in fish. ConclusionWe identified that the Fugu genome contains seven IL-17 receptor genes that are structurally similar to their other vertebrates IL-17 counterparts. The Fugu IL-17 family genes were expressed in a variety of tissues, and their expression was up-regulated by the mitogen.